Sounds so simple doesn’t it ?
In a sense it is. Players have a choice of holding, passing or shooting the puck when they have it and the last 2 games the Bruins have chosen to hold or pass waiting for the perfect shot opportunity. This is why they had 2 and 1 shots respectively in the first periods of Game 5&6.
It's like Gretzky said, "you miss all the shots you don't take".